We refresh the product feed once a day every day. If you are running a Dynamic Campaign, your products will be updated automatically and there is nothing you need to do. If your product is sold out, it will not appear in the ad carousel, and if you add new inventory this will also be reflected in your campaign within 24 hours.
The Campaign Preview we sent you is a static document we created to show you what the ad will look like. It is just an example and shows products that were current at the time the preview was created. When the preview shows incorrect product, there is no need to worry as the actual ad is running perfectly because the product feed is refreshed daily.
If you are running any other kind of campaign, the Campaign Preview we sent you shows the exact products being shown to your retargeting prospects. If these are sold out, get in touch we will change them for you. :)